Optical fiber sensor emerges as a highly promising technology for trace gas detection due to their high sensitivity, remote capability, and immunity to electromagnetic interference. However, the state‐or‐the‐art fiber‐optic gas sensors typically use lengthy optical fibers as gas absorption cells or coatings with functional materials to achieve more sensitive gas detection, which poses challenges such as slow response and/or poor selectivity, as well as limitations on their use in confined spaces. Here, an ultraminiature optical fiber‐tip photothermal gas sensor via direct 3D micro‐printing of a Fabry‐Pérot cavity on the end face of a standard single‐mode optical fiber is reported. It enables not only direct interaction between light and gas molecules at the fiber output but also remote interrogation through an interferometric read‐out scheme. With a low‐finesse microcavity of 66 µm in length, a noise equivalent concentration of 160 parts‐per‐billion acetylene gas is demonstrated with an ultra‐fast response time of 0.5 s. Such a small high‐performance photothermal gas sensor offers an approach to remotely detecting trace gases for a myriad of applications ranging from in‐reactor monitoring to medical diagnosis.

中文翻译：

---

超小型光纤尖端 3D 微印刷光热干涉气体传感器

光纤传感器因其高灵敏度、远程能力和抗电磁干扰能力而成为一种非常有前途的痕量气体检测技术。然而，最先进的光纤气体传感器通常使用长光纤作为气体吸收单元或具有功能材料的涂层来实现更灵敏的气体检测，这带来了诸如响应慢和/或选择性差等挑战。以及在密闭空间内使用的限制。本文报道了一种超小型光纤尖端光热气体传感器，通过在标准单模光纤端面上直接 3D 微打印法布里-珀罗腔来实现。它不仅可以在光纤输出处实现光和气体分子之间的直接相互作用，还可以通过干涉读出方案进行远程询问。凭借长度为 66 µm 的低精细度微腔，十亿分之 160 乙炔气体的噪声等效浓度被证明具有 0.5 秒的超快响应时间。这种小型高性能光热气体传感器提供了一种远程检测痕量气体的方法，适用于从反应堆内监测到医疗诊断等多种应用。